1897.] 



on Properties of Liquid Oxygen, 



563 



coefficient or mutual induction, neither does it involve any know- 

 ledge of the number of secondary turns on the transformer, nor of 

 the resistance of the secondary circuit ; all that is necessary for a 

 successful determination of the magnetic permeability of the liquid 

 oxygen is that the secondary circuit of the transformer should 

 remain practically of the same temperature during the time when 

 the throw of the ballistic galvanometer is being observed, both 

 with the transformer underneath the liquid oxygen and out of the 

 liquid oxygen. If then the result of reversing a current of A 

 amperes through the two primary coils in series when the secondary 

 coils are opposed is to give a ballistic throw D, and if the result of 

 reversing a small current a amperes through the primary coil of the 

 transformer alone is to produce a ballistic throw d, then, if fx is the 

 magnetic permeability of liquid oxygen, that of the gaseous oxygen 

 lying above the liquid and at the same temperature being taken as 

 unity, we have the following relation : — 



D 



a 

 •which determines the value of /x. 



Table op Results of Observations on the Magnetic Permeabilitt of 

 Liquid Oxygen. 



The values of the permeability given in the foregoing table are not 

 all of equal weight. 



The value, viz. !• 00287, found by Professor Fleming and the 

 author for the magnetic permeability of liquid oxygen, shows that 

 the magnetic susceptibility {Jc) per unit of volume is 228/ 10^ It 

 is interesting to compare this value with the value obtained by 



